This invention relates generally to registers (parallel banks of flip-flops) of the type used in digital signal processors, and more particularly to digital registers of the emitter coupled logic (ECL) family.
Master-slave flip-flops and master-slave D-registers (parallel banks of flip-flops) are used in large quantities in digital computers and digital signal processors. In these applications, flip-flops may be used with auxiliary gates and digital control circuits and in other applications registers are used to synchronize processor operation such as, for example, by capturing data from an upstream network at each edge transition of the clock signal. Also, register output signals are sometimes utilized to drive next stage networks which require true (Q), complemented (Q), or both true and complemented input signals. In other cases the output signals from several registers are connected in parallel to drive a common bus, and in this application it is usually required that each of the output signals from the registers be fed to the bus through a multiplex-enable gating arrangement so that the bus is driven only by signals from a selected register at any given time. Additionally, it may be useful to feed register output signals to a bus and in parallel to separate logic networks. Normally registers, flip-flops, gates and other specialized parts are used to serve these multiple applications.
Presently, many radars and other sensor systems are produced in relatively modest (e.g., 100-1000) quantities. Consequently, to achieve even small quantity large scale integration (LSI) part application, each part must be used many times (e.g., 100 to 1000) in each processor unit. Increasing part usage improves part quality and reliability (through higher quality fabrication) and at the same time lowers parts production and amortized non-recurring costs. Increased usage can be achieved by making one part sufficiently flexible to serve in many of the hereinabove described applications. Flexibility also reduces the number of different part types needed to build a digital processor and a requirement for a small number of LSI part types can lower initial customer resistance to LSI use and in the long run reduce inventory cost.
Numerous ECL master-slave flip-flops and master-slave D-registers are available today as standard product parts. In many cases, the prior art flip-flop circuits are similar to the one illustrated in FIGS. 1a and 1b herein, but without the output control network of FIG. 1c. The output control network of the present invention is a single series gated cascode network which might be considered similar to or derivable from the universal logic gate circuits of U.S. Pat. No. 3,925,684. However, the combination of the master-slave flip-flop and the output control network in accordance with the principles of the subject invention is not believed to have been available heretofore nor disclosed in the literature.